Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 59 users online :: 4 registered, 0 hidden and 55 guests


Most users ever online was 155 on Mon Aug 15, 2016 1:40 am

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

A few general questions, I am new at this.

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
Sponsored 
  • Author
    Message

A few general questions, I am new at this.

Unread postAuthor: brisingre » Thu May 22, 2008 12:13 am

I am building my first combustion launcher, and the design looks like this.

3" wide 3' long pvc chamber
5' long 2" wide pvc barrel
Endcap just pulls off
PVC is, I believe, pressure rated, but I don't think the fittings are.

I am wondering
A. Is this gun going to explode
B. If so, how do I fix that
C. Otherwise, how much hairspray should I use (approximately, and I know propane is better, but this is for one of my friend's birthday and I don't have time to rig it up for propane)

Thanks in advance.
  • 0


brisingre
Private
Private
 
Posts: 11
Joined: Sat May 03, 2008 9:12 pm
Reputation: 0

Unread postAuthor: BC Pneumatics » Thu May 22, 2008 12:31 am

brisngre, there should be a message for you in your inbox. :)
  • 0

<a href="http://www.bcarms.com/"><img src="http://www.bcarms.com/images/store_logo.png" border="0"> </a>
User avatar
BC Pneumatics
Donating Member
Donating Member
 
Posts: 1089
Joined: Tue Jan 18, 2005 6:55 pm
Location: Fresno, CA
Reputation: 0

Unread postAuthor: Hydra » Thu May 22, 2008 1:42 am

The end cap will come off really loudly and might hit you. You better make it a screw one.

You should actually use a ball valve for venting and fueling. Add a ball valve to the end. Or shove a reducer on and a smaller ball valve.
  • 0

User avatar
Hydra
Sergeant First Class
Sergeant First Class
 
Posts: 131
Joined: Sat Mar 08, 2008 11:58 pm
Location: New South Wales, Australia
Reputation: 0

Unread postAuthor: BigGrib » Thu May 22, 2008 2:04 am

I think you should explore this forum a little bit more and see if you can find some answers before posting. There are quite a few topics on this subject that can you can find by using the search feature. We also have a very comprehensive Wiki that will answer most of your questions. I'm not being a (expletive deleted) this is what any moderator would tell you.
  • 0

Yea, that's definitely going to get you at least a tazer.

<a href="http://www.youtube.com/watch?v=AkMkGOpAF4s">DONT TAZE ME BRO.. DONT TAZE ME... AHHHH</a>
facebook.com/biggrib
User avatar
BigGrib
Colonel
Colonel
 
Posts: 652
Joined: Mon Oct 01, 2007 11:43 pm
Location: TriCities, WA
Reputation: 0

Unread postAuthor: TurboSuper » Thu May 22, 2008 6:51 am

The ratio looks fine, although you're definitely going to want a threaded endcap. I'm not sure how much hairspray to spray in, that's a trial/error sort of thing.
  • 0

"If at first you dont succeed, then skydiving is not for you" - Darwin Awards

TurboSuper
Brigadier General
Brigadier General
 
Posts: 986
Joined: Thu Jun 16, 2005 1:44 pm
Reputation: 0

Unread postAuthor: TwitchTheAussie » Thu May 22, 2008 7:17 am

Well thats about it. All I can add is make sure you have a decent handle, sparker and ammo. Make sure you don't point it at anyone or be an idiot with it. Also like the Eragon name of fire :wink:
  • 0

Raise your horns if you love metal.
spudgunning is like sex, once you've tasted, you can't wait til next time.
-
CpTn_lAw
User avatar
TwitchTheAussie
Brigadier General
Brigadier General
 
Posts: 980
Joined: Tue Feb 06, 2007 3:23 am
Reputation: 0

Re: A few general questions, I am new at this.

Unread postAuthor: jimmy101 » Thu May 22, 2008 9:59 am

I am wondering
A. Is this gun going to explode

Yes. Not a chance in hell that the end cap will stay on.
B. If so, how do I fix that
Glue on a cleanout.
C. Otherwise, how much hairspray should I use (approximately, and I know propane is better, but this is for one of my friend's birthday and I don't have time to rig it up for propane)
Use a <a href="http://www.inpharmix.com/jps/Fuel%20Meter%20From%20A%20Disposable%20Butane%20Lighter.html">disposable $0.49 butane lighter and a short length of wire insulation</a>. Cheaper, easier, more effective, and cleaner than hairspray.
  • 0

Image

jimmy101
Lieutenant General
Lieutenant General
 
Posts: 3128
Joined: Wed Mar 28, 2007 9:48 am
Location: Greenwood, Indiana
Country: United States (us)
Reputation: 7

Re: A few general questions, I am new at this.

Sponsored

Sponsor
 


Unread postAuthor: pat123 » Thu May 22, 2008 10:06 am

http://www.spudfiles.com/spud_wiki/index.php?title=Combustion_cannon
here is the wiiki page for combustion guns.
post some pics so we can see the pipe to make sure it is ok too use.
  • 0

User avatar
pat123
Colonel
Colonel
 
Posts: 514
Joined: Sat Dec 23, 2006 10:08 pm
Location: S.C.
Reputation: 0

Unread postAuthor: CS » Thu May 22, 2008 10:29 am

While the sizes & lengths you have listed will work, I'd suggest slightly different sizes:

4" diameter chamber, 1.5' long
1.5" diameter barrel, 4' long

After about my third basic combustion I started making my cannons to these rough dimensions. I like the 1.5" barrel over the 2" barrel because most potatoes will fit, and I seem to get longer range out of it. As well I prefer the 4" chamber over the 3" chamber because you get more chamber space in a shorter length.

Then for the end your going to want a female adapter with a threaded plug.

As to your questions:
A - The truth is mostly no. Long time memebers are hesitant to absolutely say "no" because we know in rare cases guns have exploded, but the worst thing that could happen in the case of your gun is that the cleanout cap blows off. So you gotta be careful because I have had them shatter on concrete and hit people/things.
B - Already kinda answered that.
C - For the dimensions I gave you, 1-2 seconds. For the dimensions you gave I'd guess 3 seconds, maybe 4.
  • 0

User avatar
CS
Donating Moderator
Donating Moderator
 
Posts: 1897
Joined: Fri Feb 18, 2005 5:32 pm
Location: Southern Utah
Country: United States (us)
Reputation: 4

Unread postAuthor: Boom_erang » Thu May 22, 2008 1:47 pm

pimpmann22 wrote:While the sizes & lengths you have listed will work, I'd suggest slightly different sizes:

4" diameter chamber, 1.5' long
1.5" diameter barrel, 4' long


That's a fairly hefty C:B ratio... 226in3 chamber vs. 85in3 barrel... or 2.7:1. I would guess your cannon makes a pretty loud bang with quite the muzzle flash!

My first gun was 18"x3" chamber and 1.5x48" barrel, yielding a 1.5:1 ratio, still makes a bit of a bang but not too bad. Definitely can send a potato a loooong way.

My second gun is 8.5"x4" chamber and 44" barrel, yielding approximately a .8:1 ratio, and it seems to work amazingly well. Very efficient and fast, and not too loud at all. The silencer helps, too. I'm using static guard with both guns, which has performance similar to propane when mixed right.

-B
  • 0

User avatar
Boom_erang
Corporal
Corporal
 
Posts: 61
Joined: Fri Apr 25, 2008 2:26 pm
Reputation: 0

Unread postAuthor: brisingre » Thu May 22, 2008 6:12 pm

Ok. I have added a screw on end cap. Sorry I didn't check the wiki. Thanks for all your help, guys.
  • 0


brisingre
Private
Private
 
Posts: 11
Joined: Sat May 03, 2008 9:12 pm
Reputation: 0

Return to Combustion Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

Reputation System ©'